Various devices that generate data are distributedly deployed. For example, a smart phone generates log data of the Global Positioning System (GPS), pictures, videos and the like, and a sensor device generates monitoring data. Such data is collected through a network including plural nodes, and is used by applications used by an end user and/or is used for control based on the monitoring.
A specific example of such a system is a disaster alert system. In this system, measurement data is always collected from a water level sensor of a river, an accelerometer or the like, and when a value of the measurement data exceeds a threshold, an alert is issued. In such a system, it is desired that a dangerous state that the value of the measurement data exceeds the threshold is recognized soon and is notified to citizens.
Moreover, a certain document discloses a system for delivering an appropriate advertisement according to properties and/or a state of a user such as a behavioral targeting advertising system. This is a system to display a recommended advertisement by a human preference (e.g. purchase history), a temperature of a location and/or the like. For example, when an advertisement content that corresponds to the preference of the purchaser and/or the temperature is displayed by a vending machine that has a display device, an identifier of the purchaser is obtained, and then, the advertisement content is delivered from the content delivery server in a short time to cause the display device of the vending machine to display the advertisement. Therefore, a transmission time is calculated based on the arrival time limit to the vending machine, the time required for data transmission and the like, and the data transmission is performed according to the calculated transmission time. However, when the same transmission time is calculated for a lot of data, the congestion occurs.
Moreover, another certain document discloses a communication system to communicate through a transmission line between a main apparatus and plural sub-apparatuses. Then, the sub-apparatus transmits an information amount of an information signal to be transmitted through the transmission line to the main apparatus, and the main apparatus calculates an information amount of information that the sub-apparatus can transmit based on the information amount received from the sub-apparatus, and transmits the calculated information amount to the sub-apparatus. In response to this, when the sub-apparatus receives the information amount of information that the sub-apparatus can transmit, the sub-apparatus transmits an information signal having the received information amount.
The main apparatus in such a communication system determines the information amount of the information that the sub-apparatus can transmit, only based on the received information amount, and cannot determine contents of information to be transmitted by the sub-apparatus, individually. Therefore, the transmission to the main apparatus may be delayed.
Patent Document 1: Japanese Laid-open Patent Publication No. 2011-61869
Patent Document 2: Japanese Laid-open Patent Publication No. 2000-270010
Patent Document 3: Japanese Laid-open Patent Publication No. 2013-254311
In other words, there is no conventional art that can sufficiently suppress the delay of the data transmission.